Princeton's WordNet

1. subacute sclerosing panencephalitis, SSPE, inclusion body encephalitis, subacute inclusion body encephalitis, sclerosing leukoencephalitis, subacute sclerosing leukoencephalitis, Bosin's disease, Dawson's encephalitis, Van Bogaert encephalitis(noun)

   a rare chronic progressive encephalitis caused by the measles virus and occurring primarily in children and young adults; death usually occurs within three years; characterized by primary measles infection before the age of two years